Herpes spreads through direct skin-to-skin contact with someone who carries the virus, whether or not they have visible sores at the time. There are two types: HSV-1, which typically causes oral herpes (cold sores), and HSV-2, which usually causes genital herpes. Both are extremely common, and most people who have the virus don’t know it because they’ve never had noticeable symptoms.
How HSV-1 Spreads
HSV-1 passes from person to person through contact with sores, saliva, or skin surfaces in and around the mouth. Kissing is the most common route. Sharing utensils, cups, or lip products carries a lower risk, but the virus can technically survive on dry surfaces for anywhere from a few hours to several weeks depending on conditions like humidity and temperature. That said, direct contact with an infected person’s skin or saliva is far and away the primary way people pick it up.
Most people acquire HSV-1 during childhood from a parent or family member, often without anyone realizing transmission happened. The greatest risk is when someone has an active cold sore, but the virus can also spread from skin that looks completely normal.
What surprises many people: HSV-1 is now a major cause of genital herpes, transmitted through oral sex. Research from MIT Health found that nearly 80% of college students diagnosed with genital herpes had HSV-1 rather than HSV-2, likely because of high rates of oral sex in that age group. If someone has oral HSV-1 and performs oral sex, they can pass the virus to their partner’s genitals.
How HSV-2 Spreads
HSV-2 transmits through genital-to-genital or genital-to-anal skin contact during sex. It does not commonly spread through oral sex. Unlike HSV-1, which most people get in childhood, HSV-2 is almost exclusively acquired through sexual activity.
Biology plays a role in who catches it. Women are significantly more likely to acquire genital herpes from a male partner than the reverse. Studies of couples where one partner had HSV-2 found annual transmission rates of 11 to 17% when the male partner was the carrier, compared to just 3 to 4% when the female partner was the carrier. This difference is largely due to anatomy: mucosal tissue in the genital area is more exposed in women, giving the virus easier entry.
Transmission Without Symptoms
This is the part that catches most people off guard. About 70% of herpes transmissions happen during periods when the infected person has no symptoms at all. The virus periodically reactivates and travels to the skin surface, releasing small amounts of virus in a process called “shedding,” even when there are no sores, tingling, or any other signs.
How often this happens depends on the type of herpes and how long someone has had it. HSV-2 sheds frequently: roughly 34% of days in the first year after infection, dropping to about 17% of days by year ten. Genital HSV-1 sheds less often, starting around 12% of days in the first few months and falling to about 7% by the end of the first year. Over time, shedding can drop even further, to as low as 1.3% of days for HSV-1.
The practical takeaway: someone can pass herpes to a partner on a day when they feel perfectly fine and have no visible outbreak. This is the single biggest reason herpes continues to spread so widely.
What Raises Your Risk
Several factors make transmission more likely:
- Unprotected sex. Skipping condoms or dental dams removes a physical barrier that reduces (though doesn’t eliminate) risk.
- Multiple or anonymous partners. More partners means more potential exposure to someone shedding the virus without knowing it.
- Having another STI. A current or past sexually transmitted infection can make the genital tissue more vulnerable to HSV.
- Contact during an active outbreak. Viral load is highest when sores are present, making transmission far more likely than during asymptomatic shedding.
- New infections in a partner. Shedding is most frequent in the months right after someone first contracts herpes, so a recently infected partner poses higher risk even without symptoms.
How Quickly Symptoms Appear
If you do develop symptoms after exposure, they typically show up within six to eight days, though the range spans anywhere from one to 26 days. The first outbreak is usually the most noticeable: clusters of small, painful blisters or sores around the mouth (for oral herpes) or the genitals and surrounding area (for genital herpes), sometimes accompanied by flu-like feelings, swollen glands, or body aches.
Many people, however, never get a recognizable first outbreak. Their initial infection is so mild it goes unnoticed, or they mistake it for something else entirely, like an ingrown hair or a yeast infection. This is a big part of why herpes spreads so effectively: the majority of carriers genuinely don’t know they have it.
How Condoms and Antivirals Reduce Risk
Condoms lower the risk but don’t eliminate it, because herpes can live on skin that a condom doesn’t cover. One large study found that 8% of people who never used condoms acquired HSV-2, compared to 4.6% of those who used condoms more than 75% of the time. That’s roughly a 40% reduction in risk with consistent use. Higher frequency of condom use corresponded to lower rates of infection in a clear stepwise pattern.
Daily antiviral medication taken by the infected partner also cuts transmission risk. The CDC notes that daily suppressive therapy with a common antiviral decreases the rate of HSV-2 transmission in couples where only one partner is infected. When combined with condoms, the two strategies together offer the strongest protection available short of abstaining from contact with the affected area.
Less Common Routes
In rare cases, a mother with herpes can pass the virus to her baby during vaginal delivery, which is called neonatal herpes and can be serious. This is most likely when the mother has a new, active infection close to the time of delivery rather than a long-standing one.
Transmission through contaminated objects like towels or razors is theoretically possible since the virus can survive on surfaces, but it’s not considered a meaningful real-world risk. The virus is fragile outside the body, and the vast majority of infections trace back to direct skin-to-skin or skin-to-mucous-membrane contact with another person.